1. Field of Invention
This invention pertains to a novel rail fastener, and more particularly, to a fastener formed of an abrasion plate resting on the railroad tie, a pad disposed on the plate and supporting the rail and a pair of insulators disposed on the side of the pad. Means are provided to bundle the abrasion plate, the pad and the insulators so that they can be stored, shipped and installed easily as a single unit.
2. Description of the Prior Art
During the last decades, the old wooden ties used to support railroad rails were replaced by concrete ties and pads were provided between the rails and the concrete ties. These pads provided two functions: they acted as shock absorbers for the rails and they provided electrical insulation. This latter function is important for railroad systems in which the rails form a part of the electrical circuitry for either the motive power, signaling or control functions. Separate rail clips or other similar fasteners are used to clamp the rail to the ties. For example, commonly owned U.S. Pat. No. 5,110,046, incorporated herein by reference, discloses a two part rail fastener: an elastomeric pad and an abrasion plate resting on the tie. The abrasion plate was made of a heat treated high carbon steel. The abrasion plate was provided on its bottom surface with a layer of adhesive to secure it to the concrete tie. Other rail fasteners have been developed with an abrasion plate made of a plastic material.
The rails are retained in the assembly by a spring clip made of a steel bar. Another means of supporting a rail consists of a metal clip such as the SAFELOK® available from Pandrol® USA of Bridgeport, N.J. The clips are mounted to the pad with a pair of insulators, one insulator being disposed on each side of the rail.
However, problems still remain with rail fasteners. One problem is that, after excessive use, the concrete tie under the fastener gets worn and has to be repaired. A further problem is that over time rails tend to expand and contract longitudinally due to temperature changes, and as a result of train movement. This action tends to separate the two parts of the fastener.
A further problem with the prior art support assembly has been that its several components had to be kept together to eliminate assembling them in the field. The traditional way to implement this was to tie the components together with plastic or fiberglass tape. Tape is unsatisfactory because it is time-intensive to apply the tape. Moreover, if the tape is weak, the components could easily separate.